Britain on Thursday became the first country to formally license an in-vitro fertilization (IVF) treatment designed to create babies from three people.
Critics of the treatment say it is a dangerous step that will lead to the creation of genetically modified "designer babies."
In a long-awaited decision, Britain's Human Fertilisation and Embryology Authority (HFEA) gave the final go-ahead for the treatment known as mitochondrial transfer, which doctors say could help prevent incurable inherited diseases.